1) Field of the Invention
The field of this invention relates generally to heat exchangers and more particularly to a heat exchanger in conjunction with a pump which is mounted within a recirculating water system where the heat of the motor is utilized to raise the temperature of the recirculating water.
2) Description of the Prior Art
The structure of the present invention is designed primarily to be used in conjunction with a bathtub which includes a plurality of water jet nozzles used to create a turbulent action of the water within the bathtub for reasons of therapy and/or relaxation to a human. However, it is possible that this invention could be used with a spa, hot tub or therapy tub all of which utilize jet nozzles to force jets of water within the tub with the tub being occupied generally by a single human. It is normal for a plurality of humans to be located within a spa, hot tub or therapy tub. However, within a bathtub there is generally only a single individual. It is possible that the pump of the present invention could be used for liquids other than water.
The bathtubs which have water jet nozzles have a recirculating water system which utilizes a pump which has a motor causing rotation of a centrifugal impeller which functions to cause the water to move through the recirculating water system. It is desirable to heat the water within these bathtubs with generally this water being heated between 100 and 104 degrees Fahrenheit. A heater is sometimes included in conjunction with the bathtub with the heater functioning to raise the temperature of the recirculating water to the desired temperature level. During the time that the bathtub is being used, the heat from the water is quickly lost to the ambient atmosphere. Therefore, this heat needs to be replaced. In the past, it has been common to add additional hot water from the tap or activate a heater, if available, that is mounted in conjunction with the bathtub to reheat the water. However, it has been discovered that the electric motor of the pump of the recirculating water quickly becomes quite hot. It is desirable to have the motor temperature as low as possible to maintain an efficient operation of the motor. Therefore, it is beneficial to remove as much heat from the motor as possible.
It has been known to take some of the water that is being recirculated through the system and pass that bypass water through the motor with the idea that the bypass water is used to extract the heat produced by the motor with this heat being added back to the recirculating water. The advantage of such a heat exchange arrangement is that it increases the efficiency and longevity of operation of the motor of the pump and the heat that is normally wasted is now utilized therefore either eliminating or decreasing the requirement for an additional heater for heat to be added to the recirculating water.
In the past, it has been known to wrap a tubular coil about a pump motor and then conduct bypass water through that tubular coil to extract the heat that is produced from the motor. This prior art water bypass arrangement has been known to extract the water from the outlet side of the pump, move the water through the bypass tube and then reinject it back into the inlet side of the pump. The disadvantage of this type of an arrangement is that there is very little heat transfer between the motor and the tubular coil. The surface of contact between the tubular coil and the motor surface is almost nil. The heat transfer relies on convection rather than conduction which is the most efficient way of exchanging heat.